Coin control telephone system



July 28, 1959 E. H. GATZERT ETAL 2,897,272

com CONTROL TELEPHONE SYSTEM l5 Sheets-Sheet l Filed July 26, 1955 July28, 1959 E. H. GATzl-:RT ETAL 2,897,272

coIN CONTROL TELEPHONE SYSTEM 15 Sheets-Sheet 2 Filed July 26, 1955 July28, 1959 E. H. GATzERT ET AL 2,897,272

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com CONTROL TELEPHONE SYSTEM Filed July 26, 1955 15 SheetS-Shet 5 July28, 1959 E. H. GATZERT ET AL 2,397,272

com coNTRQL TELEPHQNE SYSTEM l5 Sheets-Sheet 7 Filed July 26, 1955 July2s, 1959 E. H. GATZERT ET AL COIN CONTROL TELEPHONE SYSTEM 15Sheets-Sheet 8 Filed July 26, 1955 llhu July 28, 1959 H. GATZERT ET ALCOIN CONTROL `TELEPHONE SYSTEMv Filed July- 26, 1955 15 sheets-#sheet 9cuTI oFF

v FIG. 8

Two wAY TRUNK cmcum A19 July 23, 1959 E. H. GATzr-:RT iET AL 2,897,272

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MARKING FIG. 9

July 28, 1959 H. GATZERT ET AL 2,897,272

G01N CONTROL TELEPHONE SYSTEM 15 Sheets-Sheet l1 Filed July 26, 1955July 28, 1959 E. H. GATzl-:Rr ET AL 2,897,272

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com coNTRor.. TELEPHONE SYSTEM 'mea July 2e, 1955 15 Sheets-Sheet 15July 2s, 1959 E. H. GATZERT r-:T AL 2,897,272

COIN CONTROL TELEPHONE SYSTEM 15 sheets-sheet 14 Filed July 26, 1955 1.5SheetS-Shee 15 N EOFOMZZOD July 28, 1959, E. H. GATzx-:RT ET AL COINCONTROL TELEPHONE SYSTEM Filed July 2e, 1955 oww ow cm2 e2: om EE 9.9 omo United States Patent F, M

COIN CONTROL TELEPHONE SYSTEM [Ernest H. Gatzert and William W. Pharis,Rochester, N.Y., assignors to General Dynamics Corporation, acorporation of Delaware Application July 26, 195'5, Serial No. 524,"520

i Claims. (Cl. I\179 6.3)

This invention relates to telephone systems and more particularly tocoin control systems for use therein.

It is old to provide telephone systems for use in connection withpaystations. The operator, in such systems, controls the disposition ofcoins which may be deposited in the coin box of the telephone to pay thecharges required for the completion of a toll call. Sometimes thiscontrol feature is arranged-so that an operator at a central office maycontrol the disposition of coins at a remote office, such as inacommunity dial oflice or the like, for example. In this case, it isnecessary to provide means whereby the operator may control oliceequipment in the community dial office.

A first object of this invention is to provide a new and improved coincontrol telephone system.

A 'second object of this invention is to provide a coin controltelephone system where an operator at a central oice may control thedisposition ofk coins at a remote oilice. i

Another object of this invention is to provide coin control in afour-wire telephone system.

Still another object of this invention is to provide a new and improvedcoin control trunk circuit.

Yet another object of this invention is to provide a coin controlselector and coin control trunk .circuit which may be used to controlthe disposition of coins on either incoming or outgoing calls.

Still another object of this invention is to provided a new and improvedtoll and local connector for use in a coin control system.

The above described objects are accomplished by means of a telephonesystem wherein a remote oflice includes a trunk circuit which may beused on either incoming or outgoing calls. In the case of outgoingcalls, a telephone connection may be extended from the remote officethrough a trunk circuit to an operator at a central or distant oiiice.In the case of incoming calls, the trunk circuit may be used to extend atelephone connection from the operator at the central or distant olliceto a local switch train in the remote oflice. A special coin controltrunk line has access to this trunk circuit by way of a coin controlselector. It may be seized responsive to the operators control at theAoiiice. The coin control selector seizes the trunk circuit over a singlepoint of access. The disposition of coins may be controlled over thispoint of access without regard to whether the call is incoming oroutgoing therefrom. Part of this local switch train includes a local andtoll connector in which relays are reused a maximum number of times toreduce the parts necessary to provide a complete unit.

It is thought that these and other objects will bev ob,

vious to those skilled in the art and that the invention may beexplained `best by means of the following description when taken inconnection with the attached drawings in which:

Fig. la shows by block diagram a telephone system using the coin controlfeatures. Items 19,I 21 and 24 of this .block diagram are in heavilyinkedrectangles, thus4 2,897,272 Patentedl July 2K8,

. 2 indicating that they are the circuits shown in detail `intheremainder of the drawings; i

Figs. 1-4 show a coin control selector; Figs. 6-8, 11 and 12 show atwo-way trunk circuit; Figs. 5, 9, 10 and 13 show details of a local andtoll f t connector; Y

I plus and minus signs. As inthe case of most telephone circuits, theplus potential is described asv connected with ground and the minuspotentialy is described as battery. It should be understood that this orany other suitable source of power may be used.

BRIEF DESCRIPTION This invention may be explained briefly bymakingreference to Fig. la. This figure shows by block diagram a telephonesystem adapted to use the coin control fea; tures of the invention. Forexample, the subscriber at paystation 10 may initiate a telephone callby removing his receiver or handset and depositing a required coin.Allotter 15 causes line nder 12 and line circuit 11 to cooperate to findthe calling line ywhich is extended through selector 14. The nexttelephone function de# pends upon the ultimate destination of -the call.For example, digit pulses transmitted from paystation A10 may causelocal rst selector 14, second selector 16 and connector 21 to seize andsignal paystation 23. On the other hand, selector 14 may be directed toa particular level from which toll calls may be completed,l such as thetenth or zero operator level, for example. In this case, a circuit iscompleted over conductors 1S,

two-way trunk circuit 19, Iand trunk line 25 to a distant office. Whenthe operator answers, the coin which was deposited at paystation 10I tomake the call is returned. The operator at position 40 may converse withthe call ing subscriber at paystation 10. Then she instructs him t todeposit in the coin box of telephone 10 a certain of coins at paystation10.

amount of money depending upon the charges for completing the call. Y

Operator 40 may use special coin control trunk lineV 26 and coin controlselector 24 to control the disposition First she directs a switch4associated with selector 24 by means of digit pulsesVv transmitted byany suitable device, such as dial 41, for example, according to thenumerical Adesignation of trunk circuit 19 through which the call has-been extended.

z For example, if the number of two-way trunk circuit trunk line 25 totrunk circuit 19. These pulses causey incoming selector 20l to seize anidle local connector', such as connector 21, for example. The'followingdigitv pulses operate connector 21 to complete the call t pay-i station23. If necessary, the operator at positionV 40 may? Yasevera t f .l

use coin control selector 24 to control the disposition of coins atpaystation 23.

The inventive features of this system reside primarily in the coincontrol systemextending through selector 24,- tWo-way trunk circuit 19,and connector 2,1.

DETAILED DESCRIPTION Y Call from paystaton 10 to operator position 40'Ihe rst call to be described is originated at paystation 10 and iscompleted through two-way trunk circuit 19 to operator position 40.Paystation 1t) is shown in the upper lefthand corner of Fig. 6.

' Seizure-Any suitable local switch train may be used to seizeconductors 18 which lead to two-way trunk circuit 19. Responsivethereto, a circuit is completed for operating calling bridge relay 730.The purpose of this relay is to seize the trunk circuit and to controlthe transmission of a seizure signal over the trunk line 2S toswitchboard 40 at the distant oiice. The circuit for operating callingbridge relay 730 may be traced from battery through the lower winding ofrelay 730, rest contacts 762, 834, the lower lefthand winding of repeatcoil RC81, rest contacts 838, 724, 624, conductor R, the local switchtrain, paystation 10 where a loop is completed to the tip conductor, andreturn over the local switch train conductors T, rest contacts 621, 721,831, the upper lefthand winding of repeat coil RC81, rest contacts 833and 761 to ground (-5-) through the upper winding of calling bridgerelay 730. Relay 730 closes its contacts 1231 to operate release delayrelay 1240 over an obvious circuit. It also closes its contacts 1232 tooperate helping sleeve, relay 820 over a circuit which may be tracedfrom battery4 through operated contacts 1232, Vrest contacts 1267, theupper winding of helping sleeve relay 820 and rest contacts 839a toground Diierential relay 820 operates since its lower winding is shuntedby the application of ground (-1-) to both of its terminals via contacts83911.

. Release delay relay 1240 is used to hold trunk circuit equipmentoperated, to control the release thereof, and to assist in certainsupervisory functions. In greater detail, release delayrrelay 1240operates over an obvious circuit when contacts 1231 close. Responsivethereto, contacts 741 close for applying a ground busy marking to sleeveconductor S. This ground also serves to hold all preceding equipment inan operated condition until the call is terminated. Contacts 742 open toprevent `any operation of pulse relay 810 on this call as it functionson incoming calls only. Contacts 743 close to prepare for control ofsupervisory relay 720 from the distant oce. Contacts 744 close -to applya ground marking to master ground conductor MG. This marking is used tohold certain equipment in an operated condition; therefore, when it isremoved that equipment falls. Contacts 1241 close to prepare for thetransmission of ring-back and paystation tones. Contacts ,1242 close;however, they have no function until the operator prepares for coincontrol. Contacts 1243 close to operate coin tone relay 1110 over thecircuit from battery through the winding of relay 1110, rest contacts1212, 1224 and operated contacts 1243 to ground (-1-). Contacts 1244close for lighting monitor lamp MON (Fig. l2) brightly as an indicationthat the circuit has been seized but has not switched through -as yet.The circuit extends from ground through the filament of lamp MON,contacts 1244, 1269, 1225 and the message supervisory conductor tobattery, notY shown. This feature relates to local supervision for thebenelit of maintenance personnel. Contacts 1246 close to prepare for pegcount or stated otherwise for a 'tratic survey. Contacts 1247 open toremove the ground marking normally applied to the all-trunks-busyconductor. 'I'his conductor provides means for indicating when alltrunks in the rank including circuit 19 are busy. That is, as eachtrunksimilar to circuit 19 betrunks-busy conductor over rest contacts 1247,1214, busy i upper winding of relay 820, contacts 1267, 1232 andbattery. This relay is used to control the application of idle linetermination, to extend a seizure signal to the distant office and togive local supervision. More par ticularly, its contacts 823 open toremove the idle line termintaion normally completed across conductorsTand R. This ytermination may be traced from conductor T over conductorT2, rest contacts 823, capacitor C81, resistor R81, rest contacts 1264,conductor R2 and conductor R. Contacts 821 open and 822 close, therebyswitching conductor M from ground to battery. The battery is appliedthrough the lament of lamp L81, operated contacts 822, conductor M, theupper winding of signal relay 840, impedance 181 and conductor R3 oftrunk line 25, to the distant olice. This marking signals the operatorat position 40 thus indicating that a call is awaiting her answer.Signal relay 840 is differentially energized at this time so that itdoes not operate.

Coin tone relay 1110 operates as explained above. Since it is assumedthat call is from a paystation, this relay is yused at this ytime tocontrol the refund of the coin originally deposited at the paystationand to transmit tone indicating that the call originated at apaystation. Contacts 611 open thereby temporarily disabling relay 710which is not required at this time. This prepares for the control of'coin refund. Contacts 1111 close to prepare acircuit for shunt relay1250. Contacts 1112 close to start common interrupter equipment whichmay be necessary to provide tones and pulses required during thecompletion of a call. Contacts 1113 close also to prepare for coinrefund. Contacts 1114 close to complete a circuit for transmittingring-back tone to inform the calling subscriber that his call is'beingcompleted. 'Ihis circuit extends from the ring-back tone conductor overrest contacts 1213, 1227, capacitor C111, operated contacts 1114, 1241,conductor R2, conductor R, rest contacts 724, 624, the local switchtrain, paystation 10 and, return over the local switch train, conductorT, contacts 621, 721, 831, the upper left hand winding of re- ,peat coilR081, contacts 833, 761 and the upper winding of'relay 730 to groundOperator answers- Nothing further happens until the operator at position40 responds to the seizure signalv and answers the call. Responsivethereto, a signal is transmittedover conductor R3, through impedance181, the upper winding of signal relay 840, conductor M, operatedcontacts 822 and the lament of lamp L81 to battery. Now, the directionof current flow is such that relay I840 operates and closes its contacts841.` Ground (-4-) is extended -to operate supervisory relay 720 overthe circuit including contacts 841, 743, and the lower winding ofsupervisory relay 720 to battery.

Relay 720 operates as an indication that the operator hasv answered.Responsive thereto, contacts 721, 722, 724 and 725 operate to reversethe direction of battery flow over conductors T and R. That is, beforethe operation of supervisory relay 720, batteryflow was from batterythrough the lower winding of calling bridge relay 730, rest contacts762, 834, the lower lefthand winding of repeat Vc oil RC81, restcontacts 838 conductor R,

rest contacts 724, 624, and the local switch train to paystation10,.,With return from paystation over the local switch train, conductorvT, .rest contacts 621, 721", 831, the upper lefthand WindingV of vrepeatcoil j RC81, rest contacts 833, 761, and the uppenwindiug of callingbridge relay 730 to ground After relay 720 has operated, this directionof current flow is reversed. Contacts 726 closeA to extend a resistancebattery marking to conductor HS for any suitable supervision purposeswhich may be required in connection: with thelocal switch train. Thiscircuit may be traced from`( battery through the resistance of thenon-inductive (NI) upper winding of relay 720, rest contacts 753,operated contacts 726, conductor HS, cable 18, and the local switchtrain to ground (-1-), as required.V Contacts 1221 have novetfect atthis time since contacts 611 are open. Contacts 1222 complete analternate holding path for release delay relay 1240. Contacts 1223 closeto operate shunt relay 1250. The circuit for operating this relayextends from ground (-1-) through operated contacts 1111, rest contacts1211, operated contacts 1223 and the winding of shunt relay 1250 tobattery. Contacts 1224 open to break the original operating circuit fromground (-l) at contacts 1243 to coin tone relay 1110. However, it doesnot release immediately, due to the charge stored on capacitor C113.This feature will bev explained below in the section entitled PaystationTone.

Heretofore, monitor lamp MON (Fig. '12) glowed brightly over a circuitwhich was traced from ground through the filament of lamp MON, operatedcontacts 1244, rest contacts 1269, 1225 and the message supervisoryconductor to a battery, not shown. Now, after relay 720 operatescontacts 1225, the lamp glows dimly over a circuit which may be tracedfrom ground through the filament of monitor lamp MON, operated contacts1244, resistor R121 and the message supervisory conductor to battery,not'shown. Contacts 1227 open to terminate ring-back tone and 1226 closeto prepare for paystation tone. Contacts 1228 close to extend -a markingto the peg count conductor thus giving a trac survey of thenumber oftimes that the trunk is used. This circuit may be traced from the pegcount conductor through operatedvcontacts 1115, 1228, 1246, restcontacts 1214, busy key contacts BK61 and rest contacts 766 to ygroundAutomatic refundshunt relay 1250 operates. The reason' for operating itat this time is to control coin refund. Since it is assumed that thecall originated in a paystation, conductor HS is marked by ground On theother hand, if the call had originated from other than a paystation,there would be no ground marking on conductor HS.v This ground markingis extended from conductor HS through contacts 726 and 752 to batterythrough the upper winding of paystation relay 620.

Relay 620 operates to refund the coin that was deposited to originatethe call. Preliminary or X contacts 626 close when relay 620 isenergized over its upper winding. The circuit for holding operated relay730 includes contacts 621 and 624 which are about to be opened. Hence,the operator will receive on-hook supervision during automatic refundwhich makes it appear that the calling subscriber has hung up. As willbe pointed out .presently, after automatic refund relay 730 will be heldin an operated condition once more from the calling subscribers station.Thus, the on-hook supervision is merely a flash. Sometimes this flash isrequired and sometimes it is unwanted. Therefore to eliminate flashsupervision, relay 620 closes its X or preliminary contacts 623 tocomplete an alternate holding circuit for relay 730 if wiring C isprovided. This circuit extends from battery, through the lower windingof relay 730, contacts 623, 713, 723, wiring C, resistor R72, contacts761 and the upper winding of relay 730 to ground (,-l-). If wiringfC isomitted,V this path is open and-dash supervision is given. A circuit iscompleted from ground through operated contacts 744 and 626 to battery,through the lower winding of relay 620. Relay 620 is lockedWhen-energized over this circuit. Paystation relay 620 closes itscontacts 622 and 625 thereby extending refund battery to operate thepaystation mechanism, thus refunding the coin that was deposited toinitiate the call. This refund battery may be traced from conductors Tand R,through operated contacts 622 and 625 in parallel, rest contacts711 and 714 in parallel, operated contacts 1113 and the filament of lampL111 to ll0 volt refund bat` tery. Contactsr1121 close; however, theyhave no effect at this time since contacts 1224 are open.

Paystaton toma-It should be recalled that relay 840 operated responsiveto the receipt of answer supervision from the distant oice. Contacts 841closed andsince release `delay relay 1240 was operated at this time,supervisory relay '720 operated. It opened its contacts 1224, thusbreaking the original energizing path to coin tone relay 1110. It shouldbe noted that capacitor C113 was charged prior to the opening ofcontacts 1224. This charging path extended from battery, throughcapacitor C113, rest contacts 1212 and 1224 and operated contacts 1243to ground (-1-). This circuit is opened at contacts 1224.Capacitor'C113v begins to discharge through the winding of coin tonerelay 1110. Therefore, relay 1110 remains in an operated condition for abrief interval of time after the operator has answered. During this,interval, a circuit is completed from the paystation tone conductor,through operated contacts 1122, 1226, capacitor C111, contacts 1114,1241, conductor R2, rest contacts 838 and repeat coil RC81 to thedistant exchange. This tone informs the operator that the call wasoriginated at a paystation. y

If the operator should `fail to hear the playstation tone and wish toverify, she will disconnect thereby'releasing signal relay 840 which inturn opens its contacts 841 to restore ysupervisory relay 720. Contacts1224 close and coin tone relay 1110 reoperates. The charging path iscompleted for recharging capacitor C113. Whenthe operator reconnects atthe distant end, supervisory relay 720 reoperates opening contacts.-1224. Responsive thereto, coin tone relay 1110 is held briey by thedischarging current from ,capacitor C113 in the manner explained before.v

'When coin tone relay 1110 releases, it opens contacts 1111 therebyrestoring shunt relay 1250. Previously, this relay has been operatedover the path which includes ground contacts 1111, 1211, 1223, thewinding of relay 1250 and` battery. Shunt relay 1250 releases.Responsive thereto, a circuit is completed for` operating coin refundrelay 710 over the circuit which may be traced from battery, through thewinding of relay 710, rest contacts 718,. 611, 1251, operated contacts1221 and 744 to vground This removes the coin refund battery formerlyextended from volt refund battery through lamp L111, contacts 1113 andin parallel over contacts 711 and 714, contacts 622 and 625, cable 18and the local switch train to pay# station 10. Contacts 712 and 715 alsocomplete the talking circuit from cable 18 over conductors T and R torepeat coil RC81. Contacts 712 and 715 are X contacts which close beforecontacts 713 open to hold relay 730 positively during transfer time ofthe contacts. After coin refund relay 710 is operated, it locks at itscontacts 717 to master ground conductor MG so that if coin tone relay1110 is reoperated to reapply coin tone, coin refund relay 710 will notrestore. Contacts 1212 open so that coin tone relay 1110 depends for itsreoperation upon the continued operation of pay-y station relay 620.Contacts 1213 open Yso that .ring-- back tone will not be returned ifthe operator verifies the paystation tone by causing supervisoryrelayj720 10,' drop and reclose contacts 122,7. AContacts 1214 open;

topreventia secondjpeg count if the operator verifies paystation tone.Coil mitch-The' operator converses with the callin subscriber .anddetermines the destination of the call. After this she computes thecharges for the completion of such calls and instructs the callingsubscriber to deposit the required 'amount of money. Thereafter, theoperator at position 40 seizes a coin control trunk line 26 (Fig. 1)which has access to a coin control selector 24. After the operator hasseized coin control trunk line 26 and has completed a circuit throughconductors CCT and CCR (the upper lefthand portion of Fig. 1), reversebattery is applied in the distant oce to conductors CCT and CCR. Thiscloses a circuit for operating pulse relay 110.' This relay controls themechanical driving of the switch responsive to the receipt of digitpulses. Contacts 311 close thereby operating release delay relay 360over the path from ground (-1-) through operated contacts 311, thewinding of release delay relay 360 and release magnet interruptorcontacts RE41 to battery. A circuit is also completed from ground (-1-)through operated contacts 3 11, resting primary olfnormal contacts PON33and the upper winding of primary delay relay 380 to battery. Contacts111 close Vto prepare a verification tone circuit so that the operatormay know that she has dialed the correct trunk circuit.

v, Release delay relay 360 operates. The purpose of this relay is tohold the circuit throughout digit pulsing, to control release and toprovide certain local supervisory features. When this relay operates, itcloses its contacts 162 to extend a circuit from ground (-1-) throughsecondary olf-normal contacts SON22, and the lower winding of secondarydelay relay 210 to battery. Monitor lamp MON (Fig. 3) is now litbrilliantly as ian indication that the coin control selector has beenseized but has not switched through as yet. The circuit for lightingthis lamp extends from ground (-1-) through operated contacts 361 and417 to battery by way 'of the ilamentof lamp MON (Fig. 3). The releasealarm conductor is opened at contacts 363 to prevent any faulty orpremature release. Contacts 362 close toprepare a circuit for coin slaverelay 460.

yPrimary delay relay 380 operates. The reason for operating this relayat this time is to prepare to mark the end of the first train of digitpulses that is to be received. Ground is applied to wiper CO fromcontacts 181. The pulsing path is prepared at contacts 183. l

Secondary delay relay 210 operates. The purpose of this relay is to markthe end of the second digit pulse train.VV It completes the preparedpulsing path at its contacts 215. Verication tone conductor VT isdisconnected :at contacts 211. Contacts 212 close to shunt firstr coinrefund relay 120 and the lower winding of coin collect relay 140. Thiscircuit is in parallel with contacts SON11 which have been closed sincethe switch was seized. Contacts 417 close to complete -a circuit forlighting lamp MON (Fig. 3) brightly. The circuit for this functionextends from ground (-1-) through operated contacts 361 and 417 tobattery through the iila mentof lamp MON (Fig. 3). The circuit is nowprepared to .receive digit pulses which are transmitted from operatorposition 40 over trunk 26. Nothing further happens these pulses arereceived.

First dgiL- Pulse relay 110 responds to each digit pulse which is abreak in the loop circuit including conductors CCT and CCR. Responsiveto each digit pulse, relay 110 releases to open contacts 311 and toclose contacts 312. This deenergizes release delay relay 360; however,it does not release throughout digit pulsing due toits slowy releasecharacteristics. Each time that contacts 312 are closed, a circuit iscompleted for operating primry'stepping magnet P thereby causing theswitch to. be driven fone step in its primary direction for each 8 digitpulse. The circuitfor this function'extends from ground.(1), throughrest contacts 12, operated contacts 161, 215, 183, the lowerwinding ofrelay 380 and primary magnet P in parallel to battery.`

Primary Aoft-normal contacts PON31, PON32 and PON33 are operatedresponsive to the first step of the switch in the primary direction.When contacts PON33 open, the original energizing circuit for primarydelay relay 380 is broken; however, this relay does not release since itis energized over its `lower winding each time that a digit pulse isreceived. Relay 380 is slow-torelease; therefore, it continues to holdthroughoutdigit pulsing yand releases only after the last pulse in thedigit pulse train has been received.

Pulse relay follows the remaining digit pulses. It opens yand closes thecircuit to primary delayvrelay 380 and primary stepping magnet Presponsive to each digit pulse. The switch is driven one step on eachpulse. On Acompletion of the digit pulse train, a loop across conductorsCCT and CCR remains closed long enough for primary delay relay 380 torestore. It opens contacts 183 and closes contacts 182 therebytransferring the pulsing path from the primary to the secondary magnet.The switch is now ready to receive the second digit pulse train.

Second digit-Again, each digit pulse is in the form of a break in theloop extending across conductors CCT and CCR. Responsive to each breakin this loop, pulse relay 110 restores to close contacts 312. This, inturn, causes the switch to step in its secondary direction at the rateof one step per pulse. The circuit for this function may be traced fromground (-1-), through rest contacts 312, operated contacts 161, 215,rest contacts 182, operated contacts 216, the upper winding of secondarydelay relay 210 and the winding of secondary magnet S in parallel tobattery. Responsive to the first switch step in thesecondary direction,secondary olf-normal contacts SON11, SON21, SON22 and SON31 areoperated. The original energizing path for secondary delay relay 210 isbroken when contacts SON22 open; however, this relay does not releaseuntil the end of digit pulsing due to the fact that it is -a slowrelease relay and due to the fact that it receives an energizing pulseover its upper winding each time that a digit pulse is received.V Whenrelay 210 releases, contacts 212 open to remove the shunt from aroundrelays andv140. Y 1

Verification toner-The switch is driven to the-particular set ofterminals which are desired. These are the terminals which areindividual to two-way trunk circuit 19. After the last digit pulse hasbeen received, secondary delay relay 210 restores. This connectsveriication tone to the talking conductors in trunk circuit 19 therebyvinforming the operator that she has dialed the correct digit since sheis listening over the original connection forthe tone. The circuit forthis verification tone may be traced from the high and verication toneconductor at contact 172 over rest contacts 131, operated contacts 111,rest contacts 211, conductor VT to Figs. 4 and 7, conductor T, restcontacts 831, the upper lefthand winding of repeat coil RC81, restcontacts 833, 761 Iand the upper winding of calling bridge relay 730 toground (-1-). This tone is induced in the righthand windings of repeatcoil RC81 and transmitted over cable 25 to operator position 40.

Monitor lamp MON (Fig. 3) isV caused to burn at a reduced level ofillumination due to the fact that contacts 417 are open and theenergization circuit for lamp MON now extends through resistor R31. Thisis an indication that the coin control selector has switched through. Acircuit is prepared for cutoif Irelay 220 when contacts 214 close.Contacts 213 close to energize coin collect relay 140. The circuit forthis function extends from battery throughy the upper winding ofvcoincollect relay `140, 'rest contacts 213, operated secondary oE-normalcontacts SON21 and operated lrest contacts 162 to ground Coin collectrelay 140 does not operate because it is differentially energized, theupper winding being energized over the previously traced circuit fromground on contacts 162 and the lower Winding being energized in serieswith conductors CCT and CCR. However, coin `refund relay 120 doesoperate in the loop including conductors CCT and CCR extending to thedistant oice. It closes its contacts 121 thereby operating a second coinrefund relay 130. Coiny refund relay 130 is slow to operate so that Iabrief interval transpires during which the verification tone istransmitted in the manner explained above to the operator -at position40. After this brief interval, lthe tone circuit is broken at contacts131. Contacts 133 close to prepare a circuit for cutoff relay 220. Thiscircuit is not effective at this time since contacts 312 are now open.

The circuit is now prepared for coin control; therefore,

the next circuit functions depend upon the sequence of events which mayhave transpired heretofore. For example, if the calling subscriberdeposited a proper amount, the operator may proceed to collect the coinsat this time. On the other hand, there may be occasions when she wouldproceed to refund the coins.

. Coin collecLf-The operator at the distant oiiice depresses a properkey for controlling coin collection. The direction of battery ow overconductors CCT and CCR is reversed. This reverses the direction ofbattery flow 'through the lower winding of dilferential coin collectrelay 140. The flux in the lower winding of relay 140 now aids the ux inthe upper winding thus causing the relay to operate. Contacts 141 closethereby operating a second coin collect relay 150.

Relay 150 operates and closes its contacts I152 thus causing thermistorTH21 to heat. This device is arranged so that its resistance goes down.as a function of the time over which it is heated. Hence, over thebrief interval of time when thermistor TH21 is heating, cutolf relay 220does not receive enough current to operate. However, after theexpiration of this brief interval of time, relay 229 will receive enoughcurrent and will operate. Contacts 351 close to prepare the path forapplying coin collect battery while contacts 352 open to break the pathfor applying coin refund ibattery. Contacts 353 close to operate coincollect relay 370.

When relay 370 operates, it prepares a path for extending a special toneto conductor CT. This tone path may be traced from a low tone conductorthrough con-` tacts 371, 171, 222 and 261 (both of which are now open)to conductor CT. The lower tone provides a distinctive coin collectsignal.

By this time, thermistor TH21 will have heated suflciently to causecutoif relay 220 to operate. It closes its contacts 223 therebyby-passing and protecting thermistor TH21. A ground (Jr) marking isapplied through X or preliminary contacts 221 to cutoff conductor CO.VThis ground marking is extended to trunk circuit 19 and over operatedcontacts 1242 to energize cutolf relay 830'.

Relay 830 opens contacts 835m and closes contacts 839b, therebyswitching the marking extended to conductor HS4 through the upperwinding of helping sleeve relay 820 from ground on contacts 839a tobattery on contacts 11245. This has no effect in this particular call.Contacts 832 and 839 close thereby placing a short circuit acrossconductors T and R. Contacts 831 and 838 open thereby -breaking thetalking connection to repeat coil RC81. This is in preparation for theapplication of collect or refund potential to the talking conductors.Contacts 833 and 834 open to break the connection to calling bridgerelay 730; however, it does not release at this time because a holdingpath is completed over the following circuit: from battery,.` throughthe lower winding of calling 'bridge relay 730, rest contacts 762,operated contacts 836, resistor R72, rest contacts 761 and the upperwinding of calling, bridge fro' relay 730 to ground It should be notedthat con-l tacts 836 are preliminary or X contacts which are adapted tomake before contacts 833 and 834 break thus furnishing a positiveholding circuit for calling bridge relay 730.

A distinctive tone lis now transmitted to the operator, informing her ofthe fact that a coin control potential is applied to conductors T and R.This distinctive tone may be traced from the low tone source throughcontacts 371, 171, operated contacts 222, control tip conductor CT,operated contacts 835, the lefthand windings of repeat coil RC81 andoperated contacts 837 to ground through capacitors C82. This tone isrepeated through repeat coil RC81 to the operator at position 40 in thedistant exchange.

Returning to the operation of the cutoff relay 220, it also closes itscontacts 421 thereby applying a ground (-1-) potential to the startconductor. This initiates the operation of suitable common equipmentwhich furnishesy various tones, pulses and currents that are necessaryto complete the call. A circuit is completed at contacts 422 for holdingcoin collect relay 370I in an operated condition. This holding circuitincludes contacts 372 and 422. Contacts 423 close to prepare part of aholding circuit for Various relays in the coin control selec-l tor.Responsive thereto, coin slave relay 460 operates, its energizingcircuit being traced from battery, through the winding of relay 460,operated contactsk 362, rest contacts 464, 451, `and operated contacts423 to ground (et).

Relay 460 operates to control the disposition of the coin. An alternatepath is closed at contacts 261 for applying the low tone indicatingcollection over the talking trunk to the operator. A circuit is alsocompleted for operating primary del-ay relay 380. This circuit may betraced from battery, through the upper winding of primary delay relay380, operated primary olfnormal contacts PON32, operated contacts 262,operated secondary oi-normal contacts SON21, and operated contacts 162to ground (-1-). The upper Iwinding of start relay 440 is connected atcontacts 461 to a 6() i.p.m. conductor. The lower winding of start relay440 is energized through an obvious circuit including contacts 462. Aholding circuit for lockout relay 450 is prepared at contacts 465.

Start -relay 440 is used to start the period during 'which the coincontrol potential is applied to the line. If a` ground pulse is presenton the 60 i.p.m. conductor when start relay .440 is connected thereto,it ywill not operate because it is then differentially energized due tothe current owing in the upper and lower winding with the magnetic iluxin the two windings opposing each other. This prevents the sending of aninitial pulse of coin control volt-age which is too short to operate thecoin collecting mechanism at the paystation. When ground is removed fromthe 60 i.p.m. conductor, start relay 440 operates over its lowerwinding, the upper winding being then deenergized. A locking circuit forcoin collect relay is completed at contacts 241 and contacts 151. Analternate ground marking is applied to the start conductor at contacts`442. A path is prepared at contacts 441 for extending coin collectbattery. Contacts 444 close to place coin interrupt relay 430 under thecontrol of the 60 i.p.m. ground pulses extended from a commoninterruptor through contacts 461.

When primary delay relay 380 reoperates, it opens a furtherpoint in therelease alarm conductor at contacts' 381 and applies an alternate groundto conductor CO at contacts 181.

When the next ground pulse appears on the 60 i.p.rn. conductor, coininterrupt relay 430 is operated. It is used to apply collect batterypulse fashion thereby Shak ing the coin control mechanism at the rate of60 i.p.m. Its energizing circuit extending Ifrom the '60 i.p.m. conductor through operated contacts 461 and 444 to (-)v`

